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Dear Mahesh/George
I can add a little here. Power supply vendors, and (I think safety
standards) assume that AC input voltage will be nominal plus or minus
10%. Thus the 264 volts quoted below will work with 240V +10% and the
180 volts is for a 200V supply -10%. These figures can all be divided
by two for the lower input ranges. That is 90 - 132 volt supply will
cope with nominal inputs of 100, 110 and 120VAC plus or minus 10%.
Outside this range, the power supply is outside this specified safe
range. So the question is, will brown outs go outside this plus or
minus 10%
For example, in a Japanese 100V system, can the voltage go below 90VAC
in a brown out? What is the lowest likely to be seen in the US? Is a
power supply allowed to burn out when run outside spec. It is intuitive
that it could at higher than rated inputs, but less so at lower than
rate voltage.
George
Mahesh Banodkar wrote:
>
> Dear George
>
> Brown out condition may occur during peak periods of utility usage
> whereby the mains voltage drops to a level well below the minimum
> voltage required to operate a critical load, and the duration of this
> condition may be sec (or Hours in case of UPS, which is battery backed
> up).
>
> Generally minimum voltage at which the safe operation of the power
> supply is guaranteed is specified in the Input Voltage specification
> (Typically 180V to 264 V for 240V mains system.)
>
> I hope this will help
>
> > -----Original Message-----
> > From: Sparacino,George [SMTP:[email protected]]
> > Sent: Wednesday, 23 June 1999 4:57
> > To: [email protected]
> > Subject: Brown-out..
> >
> >
> > Good Afternoon Folks...
> >
> > I am being asked to provide specific brown-out voltage values for our
> > power
> > supplies. When we measured several supplies (of the same type) we
> > came up
> > with a range in which brown-out occurs.. not a specific voltage.
> >
> > 2 Questions:
> >
> > 1.) Could anyone give me a definition / explanation of the term
> > "Brown-Out"
> > as applied to switching power supplies ?
> >
> >
> > 2.) Does one normally spec Brown-Out voltage as a specific value ? Or
> > as
> > within a range below the lower operating limit of a switching power
> > supply ?
> >
> >
> > Thanks for your help,
> > George
> >
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